From the Department of Pediatrics, Seth G.S. Medical College and K.E.M. Hospital, Pare!, Mumbai 400 012, India.
Reprint requests: Dr. S.B. Bavdekar, Flat No 9, Bldg A2, Worli Seaside CHS, K.A.G. Khan Road, Worti, Mumbai 400 018, India.
Manuscript received: June 16, 1998; Initial review completed: July 14, 1998;
Revision accepted: October
Beta-thalassemia is one of the commonest genetic disorders afflicting Indians. Patients
of beta thalassemia major are transfusion dependent and are consequently afflicted by iron overload. Serum ferritin
level is the most commonly used parameter for judging the degree
of iron overload. As liver is one of the organs affected by iron overload, a study was carried out to determine the relationship between tomographic ally determined liver density and serum ferritin levels.
Subjects and Methods
This prospective, cross-sectional analytical study was conducted in a large general hospital. Thirty consecutive patients with beta-thalassemia major aged 2-12 years were enrolled. Ten ml of fasting venous sample was collected and centrifuged immediately and plasma was stored frozen. Serum ferritin level in all the samples was determined at one time using radioimmunoassay (Diagnostic Products Corporation).
A CT scan of abdomen was performed within 24 hours of collection of samples using Siemens HiQ
machine. Five readings of liver density were determined in each lobe avoiding biliary tract, portal vein and porta hepatis. An average of these ten readings was designated as the liver density for that patient.
Statistical analysis performed included Pearson's correlation coefficient and 't' test.
There were thirteen boys among thirty patients enrolled in the study. The serum ferritin levels ranged from 1190 ng/ml to 15,000 ng/ ml. The average serum ferritin level was 4289.4 (±3514.1) ng/ml.
The tomographic liver density measurements were normally distributed. The. mean tomographic liver
density was 98.0±12.7 (range 72.3 - 119.8)
Hounsefield units. The relationship between serum ferritin levels and tomographic liver density is depicted in Fig 1. The correlation coefficient between the variables was 0.67 (p <0.001). The relationship between serum ferIitin level (x) and tomographic liver density
(y) could be expressed by the formula: y
0.00247 x + 88.44.
Patients of beta thalassemia major develop iron overload as a result of their inability to
excrete excessive iron they receive via multiple red-cell transfusions(1). In addition, incremental iron absorption from the gut contributes to the state of iron excess(2,3). This iron gets deposited in various tissues and organs producing morphological changes and functional derangements.
As an organ, the liver is likely to reflect iron overload in the body as it has abundant blood supply and is rich in reticulo-endothelial tissue which is the primary site of iron deposition( 4). Indeed, raised hepatic iron content and morphological changes such as parenchymal damage and hepatic fibrosis have been shown to reflect iron overload(5,6). However, these investigations require performance of the liver biopsy, which is an invasive procedure. Liver density could have been determined by using either MRI or CT scan. The latter was preferred as it is more widely available and is less expensive(5,6).
Similar to earlier observations(7), our ex- ploratory study also demonstrated significant linear correlation between tomographic liver density and serum ferritin level, a parameter commonly used to determine degree of iron
overload. Other investigators have shown that tomographic liver density correlates with histopathological changes in the liver(5) and hepatic iron content(5,6,8). The relationship demonstrated by us may have clinical impli- cations as well. It can be used to settle the issue of iron overload when erroneously low levels of serum ferritin are obtained, despite obvious signs of iron overload. In addition, earlier workers have found that tomographic liver density may be a better indicator of iron overload than serum ferritin levels in patients of thalassemia major on chelation therapy(9). This is because serum ferritin represents chelatable form of iron while liver density reflects both chelatable as well as non chelatable storage forms of iron in the body.
Authors thank Dr. (Mrs) P.M. Pai, Dean, Seth G.S. Medical College and K.E.M. Hospi- tal, Parel, Mumbai for permission to publish the article and Mr. M.B. Kulkarni for assistance in statistical analysis.
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